Verbseoul.
하다 verb (adj)
어벙하다eobeonghadato be dumbish, to be stupidish

To say to be dumbish, to be stupidish politely in the present tense, use 어벙해요 (uh-buhng-hae-yoh). Below is the full conjugation of 어벙하다 across the three tenses and three everyday speech levels.

Conjugation table

TenseCasual (반말)Polite (요)Formal (합니다)
Present
어벙해
uh-buhng-hae
어벙해요
uh-buhng-hae-yoh
어벙합니다
uh-buhng-hahm-nee-dah
Past
어벙했어
uh-buhng-hae-ssuh
어벙했어요
uh-buhng-hae-ssuh-yoh
어벙했습니다
uh-buhng-hae-sseum-nee-dah
Future
어벙할 거야
uh-buhng-hahl- -guh-yah
어벙할 거예요
uh-buhng-hahl- -guh-yae-yoh
어벙할 겁니다
uh-buhng-hahl- -guhm-nee-dah

Other useful forms

Command Polite (세요)
어벙하세요
uh-buhng-hah-sae-yoh
Suggestion / Let's Polite (요)
어벙해요
uh-buhng-hae-yoh
Question Polite (요)
어벙해요?
uh-buhng-hae-yoh-?
Connective “and” — (고)
어벙하고
uh-buhng-hah-goh
Conditional “if” — (면)
어벙하면
uh-buhng-hah-myuhn
Noun form — (기)
어벙함
uh-buhng-hahm